XML 56 R30.htm IDEA: XBRL DOCUMENT v2.4.0.8
Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Tables)
 12 Months Ended
Dec. 31, 2013
Summary of Significant Accounting Policies [Abstract]  
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]
The change in the balance of the allowance for doubtful accounts, which is included in accounts receivable, net on the Consolidated Balance Sheets, is summarized as follows for the years ended December 31 (in millions):

 
2013
 
2012
 
2011
 
 
 
 
 
 
Beginning balance
$
9

 
$
9

 
$
8

Charged to operating costs and expenses, net
13

 
14

 
13

Write-offs, net
(14
)
 
(14
)
 
(12
)
Ending balance
$
8

 
$
9

 
$
9